Tumor Deposits in Gastric Cancer: A Systematic Review of the Literature With Meta-Analysis on Prevalence and Prognostic Implications

Objective: To investigate the prevalence of tumor deposits in gastric cancer patients across different T and N stages as well as other pathologic parameters. Another goal of the study is to identify the potential impact of tumor deposit positivity on 5-year overall survival. Background: Tumor deposits represent an increasingly recognized pathologic entity in resected surgical specimens of gastric adenocarcinoma patients. Their prevalence across different T and N stages and according to lymphovascular and perineural invasion, as well as across different grades remains largely unknown. Methods: We have undertaken a systematic literature review in the PubMed and Cochrane databases with meta-analysis of data from published studies. Raw data were extracted from studies to calculate the prevalence of tumor deposits across all T, N stages, positive/negative lymphovascular, and perineural invasion status, as well as according to tumor grade. Pooled prevalence for the calculated values was performed with a meta-analysis of extracted data. Pooled hazard ratios for 5-year overall survival hazard ratio were also compared among patients with and without tumor deposits, respectively. Results: Fourteen studies (14) with a total of 18,056 patients were included in the meta-analysis. The calculated incidence of tumor deposits in gastric cancer patients undergoing surgical resection with curative intent was calculated at 17.9%. An increasing prevalence was noted while progressing from T1 to T4 and N0 to N3 stages, respectively. Patients with positive lymphovascular/perineural invasion status and patients with higher tumor grades were also noted to have increased tumor deposit prevalence compared with their negative counterparts. Patients with tumor deposits positive status were found to have an increased hazard ratio for death at the 5-year overall survival mark with a value of 1.308 ( P value < 0.05). A significant degree of heterogeneity was noted across all studies, as well as a significant degree of bias, mainly because all included studies were retrospective in nature. Conclusions: Tumor deposits are a frequent clinical entity in resectable gastric cancer and should systematically be examined in surgical specimens. Their prevalence increases with increasing T, N stages and tumor grade, as well as with positive lymphovascular/perineural invasion status. Tumor deposit positive status appears to impose a worse prognosis for overall survival. Further research is required on the biologic properties of tumor deposits AND on standardization of their identification, especially in the current era of neoadjuvant treatments that are increasingly being utilized. Confirmation of our findings with high-quality prospective data should be another focus of further research.